The Langmuir-Blodgett method is one process wherein a film has been formed by transferring a monomolecular film spread out over the vapor-liquid interface onto the surface of a support. In this method, each individual molecule has surface activity, i.e., both a hydrophilic group and a hydrophobic group, and is transferred with other molecules having surface activity onto a support in the form of monomolecular film, as described in J. Am. Chem. Sco., Vol. 57, p. 107 (1935). Also, various improvements on this method have been proposed, as described in Thin Film Processes, Academic Press (1978); Langmuir-Blodgett Films, Elsevier (1980); Thin Solid Films, 68 (1), 1, 101, 135 (1980) and ibid., 99 (1-3) (1983); J. Am. Chem. Soc., Vol. 60, p. 1351 (1938); J. Colloid Interface Sci., Vol. 54, p. 430 (1976); and Thin Solid Films, Vol. 99, p. 235 (1982), ibid., Vol. 100, p. 67 (1983), and ibid., Vol. 105, p. 674 (1983).
The above methods generally involve dissolving a surface active substance in a volatile solvent such as benzene or chloroform, dropping the solution onto the surface of water and evaporating the solvent to form at the vapor-liquid interface a monomolecular layer maintaining an adequate balance between the hydrophilic group and the hydrophobic group of each individual molecule of the surface active substance. The monomolecular layer is a homogeneous solid film composed of the molecules of the surface active substance and having no interface between the molecules.
However, since these methods utilize the surface activity of each individual molecule, they are only applicable to substances having the so-called surface activity to be dissolved or dispersed in the form of molecule in a medium. That is, these methods cannot be applied to solid granules, particular those which are substantially insoluble in the medium, such as inorganic or organic pigments to be used in the coating industry and silver halides to be used in the photographic industry, to arrange them regularly in the form of film.
If these pigments could be arranged regularly in the form of film and transferred onto the support, their covering powers would be generally increased, therefore, a reduction of the coverage of pigment or silver would be achieved. In addition, properties of the coated surface such as image qualities in the photographic industry can be improved if the solid granules are arranged in such a filmy condition over the support.
Physical Review Letters, Vol. 55, p. 226 (July 1985) and ibid., Vol. 45, p. 569 (August 1980) disclose two-dimensionally regular arrangement formed by using monodisperse spherical solid latex particles and adhering the particles at an interface. However, this method provides the regular arrangement only with a limited number of the particles and thus having only a small area. Further, these references do not disclose transfer of the arranged latex particles onto the surface of a support, and the arranged latex particles cannot be transferred onto the support without losing the regularity in arrangement.
So far as silver halide photographic materials use in the photographic industry are concerned, various methods of increasing the covering power to reduce the cost have been attempted. For example, increased covering power can be generally attained by decreasing the grain size of the silver halide grains. Furthermore, the decrease in grain size can bring about improvements in granularity and sharpness. However, reducing the grain size causes a reduction in sensitivity. Therefore, it is difficult to obtain photographic materials in which the above-described factors are well balanced. As for the covering power, it can also be increased by using tabular silver halide grains. However, tabular silver halide grains are usually unstable. This is described in, e.g., Japanese Patent Application (OPI) No. 113926/83 (the term "OPI" as used herein means an "unexamined published application").
The above problems can be solved for the most part by arranging silver halide grains regularly in a filmy condition, in a photographic emulsion layer of the sensitive material. Therefore, the attainment of a nonrandom condition is the subject of many investigations in the photographic art.